Ecteinascidins (Ets), exceedingly potent antitumor agents, first isolated from the marine tunicate Ecteinascidia turbinata, especially Et 743, Et 729, Et 736 and Et 722 show significant efficacy in vivo against tumor cell lines including P388 murine leukemia, B16 melanoma, Lewis lung carcinoma, and human tumor xenograft models in mice.
Continuing studies by Rinehart et al. are directed variously toward providing adequate quantities of these compounds for clinical trials, study of their antitumor mechanism of action, and determination of structure-activity relationships. In addition, the discovery of additional Et compounds, whether minor natural components or precursor compounds, will not only provide evidence for their biosynthetic pathway, but should also be useful for with respect to determining structure-activity relationships.